Speaking at a presentation of 2001 in Toronto, Trumbull and Larson talked about the footage they’d seen which they said is in “perfectly preserved” condition. And while they didn’t screen it, it’s assumed the footage contains at least some of the 19 minutes Kubrick himself cut for pacing purposes after the premiere—including, presumably, these scenes described on the film’s IMDB page:

Some shots from the "Dawn of Man" sequence were removed and a new scene was inserted where an ape pauses with the bone it is about to use as a tool. The new scene was a low-angle shot of the monolith, done in order to portray and clarify the connection between the man-ape using the tool and the monolith.

Some shots of Frank Poole jogging in the centrifuge were removed.

An entire sequence of several shots in which Dave Bowman searches for the replacement antenna part in storage was removed.

A scene where HAL severs radio communication between the "Discovery" and Poole's pod before killing him was removed. This scene explains a line that stayed in the film in which Bowman addresses HAL on the subject.

Some shots of Poole's space walk before he is killed were removed.

And while it’s not exactly crucial stuff, 2001 has obviously been pored over for so long that seeing anything new would be something of a revelation. Although, considering the studio has apparently been sitting on this footage for a while, there’s not telling what, if anything, it plans to do with it. But now that the public knows it not only exists, but that it looks as pristine as ever, it seems plausible that they’ll eventually recognize the sales potential here and put it out in some form or another. Otherwise fans may need to stand outside the Warner Bros. monolith and, say, smack it with clubs crudely fashioned from femurs.